Liquid crystal display device

ABSTRACT

A first substrate includes a gate line extending in a first direction and a source line extending in a second direction. A first sub-common electrode is formed on the gate line. A first main-common electrode is formed along the source line so as to be connected with the first sub-common electrode. A second main-common electrode is formed extending in the second direction and facing the source line. The second main-common electrode is set to the same potential as the first main-common electrode. A second substrate includes a third main-common electrode extending in the second direction so as to face the second main-common electrode. The third main-common electrode is set to the same potential as the second main-common electrode. A second sub-common electrode is connected with the third main common electrode. The second sub-common electrode is formed so as to face the first sub-common electrode on the gate line.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2013-139788 filed Jul. 3, 2013,the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay device.

BACKGROUND

In recent years, a flat panel display device is developed briskly.Especially, the liquid crystal display device gets a lot of attentionfrom advantages, such as light weight, thin shape, and low powerconsumption. In an active matrix type liquid crystal display deviceequipped with a switching element in each pixel, a structure usinglateral electric field, such as IPS (In-Plane Switching) mode and FFS(Fringe Field Switching) mode, attracts attention.

The liquid crystal display device using the lateral electric field modeis equipped with pixel electrodes and a common electrode formed in anarray substrate, respectively. Liquid crystal molecules are switched bythe lateral electric field substantially in parallel with the principalsurface of the array substrate.

On the other hand, another technique is also proposed, in which theliquid crystal molecules are switched using the lateral electric fieldor an oblique electric field between the pixel electrode formed in thearray substrate and the common electrode formed in a counter substrate.As one example, a portion of the pixel electrode covers a gate line andshields electric field from the gate line.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute aportion of the specification, illustrate embodiments of the invention,and together with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a figure schematically showing a structure and an equivalentcircuit of a liquid crystal display device according to one embodiment.

FIG. 2 is a plan view schematically showing a structure of one pixelwhen an array substrate AR shown in FIG. 1 is seen from a countersubstrate side according to the embodiment.

FIG. 3 is an exploded perspective view schematically showing a mainlayer structure forming the array substrate AR.

FIG. 4A is a plan view schematically showing a structure of one pixel PXin the counter substrate CT shown in FIG. 1.

FIGS. 4B and 4C are figures showing alignment axes.

FIG. 5 is a cross-sectional view schematically showing the structure ofthe liquid crystal display panel LPN taken along line A-B shown in FIG.2.

FIG. 6 is a cross-sectional view schematically showing the structure ofthe liquid crystal display panel LPN taken along line C-D shown in FIG.2.

FIG. 7 is a cross-sectional view schematically showing the structure ofthe liquid crystal display panel LPN taken along line E-F shown in FIG.2.

DETAILED DESCRIPTION

A liquid crystal display device according to an exemplary embodiment ofthe present invention will now be described with reference to theaccompanying drawings wherein the same or like reference numeralsdesignate the same or corresponding portions throughout the severalviews.

According to one embodiment, a liquid crystal display device includes: afirst substrate including; a gate line extending in a first direction, asource line extending in a second direction orthogonally crossing thefirst direction, a switching element electrically connected with thegate line and the source line, a first interlayer insulating filmcovering the switching element, a first sub-common electrode formed onthe first interlayer insulating film and extending in the firstdirection, the first sub-common electrode facing the gate line, a firstmain-common electrode formed on the first interlayer insulating film andconnected with the first sub-common electrode, the first main-commonelectrode extending along the source line in the second direction, asecond interlayer insulating film covering the first sub-commonelectrode and the first main-common electrode, a second main-commonelectrode formed on the second inter insulating film and extending inthe second direction so as to face the source line, the secondmain-common electrode set to the same potential as the first main-commonelectrode, a main-pixel electrode formed on the second interlayerinsulating film and extending in the second direction so as to cross thefirst sub-common electrode, the main-pixel electrode electricallyconnected with the switching element, and a first alignment filmcovering the second main-common electrode and the main-pixel electrode;a second substrate including; a third main-common electrode extending inthe second direction so as to face the second main-common electrode, thethird main-common electrode set to the same potential as the secondmain-common electrode, a second sub-common electrode connected with thethird main common electrode, the second sub-common electrode extendingin the first direction so as to face the first sub-common electrode, anda second alignment film covering the third main-common electrode and thesecond sub-common electrode, a liquid crystal layer held between thefirst substrate and the second substrate.

According to other embodiment, a liquid crystal display device includes:a first substrate including; a gate line extending in a first direction,a source line extending in a second direction orthogonally crossing thefirst direction, a switching element electrically connected with thegate line and the source line, a gate shield electrode extending in thefirst direction and facing the gate line, a source shield electrodeextending in the second direction so as to face the source line, thesource shield electrode set to the same potential as the gate shieldelectrode, and a main pixel electrode extending in the second directionso as to cross the gate shield electrode, the main pixel electrode beingapart from the source shield electrode and electrically connected withthe switching element, a second substrate including; a main-commonelectrode facing the source shield electrode and extending in the seconddirection, the main-common electrode set to the same potential as thesource shield electrode; and a sub-common electrode connected with themain common electrode and extending in the first direction so as to facethe gate shield electrode, a liquid crystal layer held between the firstsubstrate and the second substrate.

FIG. 1 is a figure schematically showing a structure and the equivalentcircuit of a liquid crystal display device according to one embodiment.

The liquid crystal display device includes an active-matrix type liquidcrystal display panel LPN. The liquid crystal display panel LPN isequipped with an array substrate AR as a first substrate, a countersubstrates CT as a second substrate arranged opposing the arraysubstrate AR, and a liquid crystal layer LQ held between the arraysubstrate AR and the counter substrate CT. The liquid crystal displaypanel LPN includes an active area ACT which displays images. The activearea ACT is formed of a plurality of pixels PX arranged in the shape ofa (m×n) matrix (here, “m” and “n” are positive integers).

The liquid crystal display panel LPN is equipped with “n” gate lines G(G1-Gn), “n” auxiliary capacitance lines C (C1-Cn), “m” source lines S(S1-Sm), etc., in the active area ACT. The gate line G and the auxiliarycapacitance line C linearly extend in a first direction X, respectively.The gate line G and the auxiliary capacitance line C are arranged inturns along a second direction Y that orthogonally intersects the firstdirection X. The source lines S cross the gate line G and thecapacitance line C. The source lines S extend linearly in the seconddirection Y, respectively. The gate line G, the auxiliary capacitanceline C and the source lines S may not necessarily extend linearly, and aportion thereof may be crooked partly.

Each gate line G is pulled out to outside of the active area ACT, andconnected to a gate driver GD. Each source line S is pulled out to theoutside of the active area ACT, and connected to a source driver SD. Atleast a portion of the gate driver GD and the source driver SD is formedin the array substrate AR, for example. The gate driver GD and thesource driver SD are connected with the driver IC chip 2 provided in thearray substrate AR and having an implemented controller.

Each pixel PX includes a switching element SW, a pixel electrode PE, acommon electrode CE, etc. Retention capacitance Cs is formed, forexample, between the auxiliary capacitance line C and the pixelelectrode PE. The auxiliary capacitance line C is electrically connectedwith a voltage impressing portion VCS to which auxiliary capacitancevoltage is impressed.

The switching element SW is formed of an n channel type thin filmtransistor (TFT), for example. The switching element SW is electricallyconnected with the gate line G and the source line S. The (m×n)switching elements SW are formed in the active area ACT. The switchingelement SW may be either a top-gate type or a bottom-gate type. Thoughthe semiconductor layer is formed of poly-silicon, the semiconductorlayer may be formed of amorphous silicon.

The pixel electrode PE is arranged in each pixel PX and electricallyconnected with the switching element SW. The common electrode CE ofcommon potential is arranged in common to the plurality of pixelelectrodes PE through the liquid crystal layer LQ. An electric powersupply portion VS is formed outside of the active area ACT to impress avoltage to the common electrode CE. Furthermore, the common electrode CEis drawn to outside of the active area ACT and electrically connectedwith the electric power supply portion VS through an electric conductivecomponent which is not illustrated.

In addition, in the liquid crystal display panel LPN according to thisembodiment, while the pixel electrode PE is formed in the arraysubstrate AR, at least one portion of the common electrode CE is formedin the counter substrate CT. Liquid crystal molecules of the liquidcrystal layer LQ are switched mainly using an electric field formedbetween the pixel electrode PE and the common electrode CE. The electricfield formed between the pixel electrode PE and the common electrode CEis an oblique electric field slightly oblique with respect to a X-Yplane specified by the first direction X and the second direction Y,i.e., the substrates (or lateral electric field substantially inparallel with the principal surface of the array substrate AR.)

FIG. 2 is a plan view schematically showing a structure of one pixelwhen an array substrate AR shown in FIG. 1 is seen from a countersubstrate side according to the embodiment.

The array substrate AR is equipped with a gate line G1, an auxiliarycapacitance line C1, an auxiliary capacitance line C2, a source line S1,a source line S2, a pixel electrode PE, and a portion of a commonelectrode CE, a first alignment film AL1, etc. The array substrate AR isalso equipped with a switching element SW though not shown.

The auxiliary capacitance line C1 and the auxiliary capacitance line C2are arranged at intervals along the second direction Y, and extend inthe first direction X, respectively. The gate line G1 is located betweenthe auxiliary capacitance line C1 and the auxiliary capacitance line C2,and extend along the first direction X. In this embodiment, the gateline G1 is located in an approximately center between the auxiliarycapacitance line C1 and the auxiliary capacitance line C2. That is, theinterval between the gate line G1 and the auxiliary capacitance line C1in the second direction Y is approximately the same as the intervalbetween the gate line G1 and the auxiliary capacitance line C2 in thesecond direction Y. The source line S1 and the source line S2 arearranged at intervals along the first direction X, and extend in thesecond direction Y, respectively. The pixel electrode PE is arrangedbetween the adjoining source line S1 and the source line S2.

In this embodiment, the pixel PX corresponds to a square regionsurrounded with the auxiliary capacitance lines C1 and C2 and the sourcelines S1 and S2, and is formed in the shape of a rectangle whose lengthin the first direction X is shorter than the length in the seconddirection Y, as shown with a dashed line in FIG. 2. The length in thefirst direction X of the pixel PX corresponds to a pitch between thesource line S1 and the source line S2 in the first direction X, and thelength in the second direction Y of the pixel PX corresponds to a pitchbetween the auxiliary capacitance C1 and the auxiliary capacitance lineC2 in the second direction Y.

In the illustrated pixel PX, the source line 51 is arranged at theleft-hand side end in the pixel PX. Precisely, the source line S1 isarranged striding over a boundary between the illustrated pixel PX and apixel adjoining the illustrated pixel PX on the left-hand side. Thesource line S2 is arranged at the right-hand side end. Similarly, thesource line S2 is arranged striding over a boundary between theillustrated pixel PX and a pixel adjoining the illustrated pixel PX onthe right-hand side. Moreover, in the pixel PX, the auxiliarycapacitance line C1 is arranged in an upper end portion. Precisely, theauxiliary capacitance line C1 is arranged striding over a boundarybetween the illustrated pixel PX and a pixel adjoining the illustratedpixel PX on its upper end side. The auxiliary capacitance line C2 isarranged in a lower end portion. Precisely, the auxiliary capacitanceline C2 is arranged striding over a boundary between the illustratedpixel PX and a pixel adjoining the illustrated pixel PX on its lower endside. The gate line G1 is arranged approximately in a central portion ofthe pixel PX.

The switching element which is not illustrated is electrically connectedwith the gate line G1 and the source line S1, and arranged near anintersection between the gate line G1 and the source line S1. A contactportion PC is electrically connected with the switching element. Thecontact portion PC is located on the side facing the gate line G1 in aregion which overlaps with the auxiliary capacitance line C1.

The pixel electrode PE is electrically connected with the contactportion PC in the position which overlaps with the auxiliary capacitanceline C1. The pixel electrode PE is equipped with a main pixel electrodePA, a first sub-pixel electrode PB1, and a second sub-pixel electrodePB2. The main pixel electrodes PA, the first sub-pixel electrode PB1,and the second sub-pixel electrode PB2 are formed integrally orcontinuously, and electrically connected mutually.

The main pixel electrode PA is located between the source line S1 andthe source line S2, and linearly extends along the second direction Y tonear an upper end and a bottom end of the pixel PX. In this embodiment,the main pixel electrode PA is located in an approximately centerbetween the source line S1 and the source line S2. That is, the intervalbetween the source line S1 and the main pixel electrode PA in the firstdirection X is approximately the same as the interval between the sourceline S2 and the main pixel electrode PA. The main pixel electrode PA isformed in a stripe shape with substantially the same width along thefirst direction X.

The first sub-pixel electrode PB1 lineally extends between the sourceline S1 and the source line S2 along the first direction X. The firstsub-pixel electrode PB1 is connected with an end portion of the mainpixel electrode PA, and located on the side facing the gate line G1 inthe region which overlaps with the auxiliary capacitance line C1.Moreover, at least a portion of the first sub-pixel electrode PB1overlaps with the contact portion PC, and is in contact with contactportion PC. The first sub-pixel electrode PB1 is formed in a stripeshape with substantially the same width W1 along the second direction Y.

The second sub-pixel electrode PB2 lineally extends between the sourceline S1 and the source line S2 along the first direction X. The secondsub-pixel electrode PB2 is connected with the other end portion of themain pixel electrode PA, and located on the side facing the gate line G1in the region which overlaps with the auxiliary capacitance line C2. Thesecond sub-pixel electrode PB2 is formed in a belt shape withsubstantially the same width W2 along the second direction Y.

Although not illustrated, one auxiliary capacitance line is arrangedstriding over two pixels which adjoin in the second direction Y. Thefirst sub-pixel electrode PB1 of the pixel electrode of one pixel andthe second sub-pixel electrode PB2 of the pixel electrode of theadjacent pixel are arranged at intervals in the region which overlapswith the auxiliary capacitance line. While the first sub-pixel electrodePB1 is formed broadly to secure an area required for contacting with thecontact portion PC, the second sub-pixel electrode PB2 may function asan electrode for forming electric field. For this reason, the width W1of the first sub-pixel electrode PB1 is larger than the width W2 of thesecond sub-pixel electrode PB2.

The common electrode CE is equipped with a first main-common electrodeCA1, a second main-common electrode CA2, and a first sub-commonelectrode CB1. The first main-common electrode CA1 and the firstsub-common electrode CB1 are integrally or continuously formed, andelectrically connected mutually. While the second main common electrodeCA2 is arranged apart from the first main common electrode CA1, etc.,the second main common electrode CA2 and the first main common electrodeCA1 are electrically connected mutually. That is, the first main commonelectrode CA1 and the second main common electrode CA2 are connectedwith an electric power supply portion VS on outside of the active areaACT, and set to the same potential each other.

The first main-common electrode CA1 extends along the source line S. Thefirst main-common electrode CA1 is located on the both sides sandwichingthe main pixel electrode PA in the X-Y plane, and linearly extends alongthe second direction Y. The first main-common electrode CA1 is arrangedon the pixel electrode PE side rather than the position which overlapswith the source line S. The first main-common electrode CA1 is formed ina stripe shape with the same width along the first direction X.

In this embodiment, the first main-common electrode CA1 is arranged intwo parallel lines in the first direction X, and is equipped with afirst main-common electrode CAL1 located in the left-hand side end, anda first main-common electrode CAR1 located in the right-hand side end ofthe pixel PX. While the first main-common electrode CAL1 extends alongthe source line S1 and is arranged on the pixel electrode PE side ratherthan the position which overlaps with the source line S1, a portionthereof may be arranged overlapping with the source line S1. Similarly,while the first main-common electrode CAR1 extends along the source lineS2 and is arranged on the pixel electrode PE side rather than theposition which overlaps with the source line S2, a portion thereof maybe arranged overlapping with the source line S2.

The first sub-common electrode CB1 extends along the gate line G1. Thatis, the first sub-common electrode CB1 linearly extends along the firstdirection X in the X-Y plane. The first sub-common electrode CB1counters with the gate line G1. The first sub-common electrode CB1 isformed in a stripe shape. The electrode width of the first sub-commonelectrode CB1 in the second direction Y is larger than the width of thegate line G1 in the second direction Y, for example. That is, the firstsub-common electrode CB1 is arranged in the position which overlaps withthe gate line G1. The first sub-pixel electrode CB1 is connected withthe first main-common electrode CA1.

The second main-common electrode CA2 counters the source line S. Thatis, the second main-common electrode CA2 is located on the both sidessandwiching the main pixel electrode PA in the X-Y plane, and linearlyextends along the second direction Y. The second main-common electrodeCA2 extends substantially in parallel to the first main-common electrodeCA1. The second main-common electrode CA2 is formed in a stripe shapewith a smaller width than the width of the source line S andsubstantially the same width along the first direction X.

In this embodiment, the second main-common electrode CA2 is arranged intwo parallel lines at intervals in the first direction X, and includes asecond main-common electrode CAL2 located on the left-hand side of thepixel PX and arranged striding over a boundary between the illustratedpixel PX and a pixel adjoining the illustrated pixel PX on the left-handside, and a second main-common electrode CAR2 located on the right-handside of the pixel PX and arranged striding over a boundary between theillustrated pixel PX and a pixel adjoining the illustrated pixel PX onthe right-hand side. The second main-common electrode CAL2 extends alongthe first main-common electrode CAL1 with a smaller width than the widthof the source line S1, and is arranged in a location overlapping thesource line S1. The second main-common electrode CAL2 crosses the firstsub-pixel electrode CB1 on the source line S1. Further, the secondmain-common electrode CAR2 extends along the first main-common electrodeCAR1 with a smaller width than the width of the source line S2, and isarranged in a location overlapping the source line S2 so as to cross thefirst sub-pixel electrode CB1 on the source line S2.

In the array substrate AR, the pixel electrode PE and the secondmain-common electrode CA2 are covered with the first alignment film AL1.Alignment treatment is carried out to the first alignment film AL1 alongwith an alignment treatment direction PD1 to initially align liquidcrystal molecules of the liquid crystal layer LQ. The alignmenttreatment direction PD1 is substantially in parallel to the seconddirection Y, for example.

FIG. 3 is an exploded perspective view schematically showing a mainlayer structure forming the array substrate AR. In addition, the mainelectric conductive layers in the array substrate AR are illustratedhere.

A first insulating film 11 is interposed between a first layer L1 and asecond layer L2, a second insulating film 12 is interposed between thesecond layer L2 and a third layer L3, a third insulating film 13 isinterposed between the third layer L3 and a fourth layer L4, and afourth insulating film 14 is interposed between the fourth layer L4 anda fifth layer L5.

In the first layer L1, a semiconductor layer SC of the switching elementis formed. For example, the semiconductor layer SC is formed withpoly-silicon. The semiconductor layer SC extends under the source lineS1 to an under portion of the auxiliary capacitance line C1 intersectingthe gate line G1. A region of the semiconductor layer SC located underthe gate line G1 forms a channel region SCC, a region of thesemiconductor layer SC on the side in which the semiconductor layer SCcontacts with the source line S1 forms a source region SCS, and a regionof the semiconductor layer SC extending to the under portion of theauxiliary capacitance line C1 from the channel region SCC forms a drainregion SCD.

In the second layer L2, the auxiliary capacitance line C1, the gate lineG1, and the auxiliary capacitance line C2 are arranged. The auxiliarycapacitance line C1 is located above the drain region SCD. An apertureportion AC is formed in the auxiliary capacitance line C1 correspondingto the drain region SCD. In the gate line G1, a region located above thesemiconductor layer SC corresponds to a gate electrode WG of theswitching element.

In the third layer L3, the source line S1, the source line S2, and thecontact portion PC are arranged. The source line S1 is located above aportion of the semiconductor layer. In the source line S1, a regionwhich contacts the semiconductor layer SC corresponds to a sourceelectrode WS of the switching element. That is, the source electrode WSis in contact with the source region SCS through a contact hole whichpenetrates the first insulating film 11 and the second insulating film12. The contact portion PC is located above the auxiliary capacitanceline C1. The contact portion PC corresponds to a drain electrode of theswitching element. That is, the contact portion PC is in contact withthe drain region SCD through a contact portion which penetrates thefirst insulating film 11 and the second insulating film 12, and theaperture portion AC.

In the fourth layer L4, the first main-common electrode CAL1, the firstmain-common electrode CAR1, and the first sub-common electrode CB1 arearranged. The first main-common electrode CAL1 is located on an innerside of the pixel PX rather than above the source line S1. The firstmain-common electrode CAR1 is located on the inner side of the pixel PXrather than above the source line S2. The first sub-common electrode CB1is located above the gate line G1.

In the fifth layer L5, the second main-common electrode CAL2, the secondmain-common electrode CAR2, and the pixel electrode PE are arranged. Thesecond main-common electrode CAL2 is located above the source line S1.The second main-common electrode CAR2 is located above the source lineS2. The main pixel electrode PA of the pixel electrode PE intersects thefirst sub-common electrode CB1 in two levels through the fourthinsulating film 14. The first sub-pixel electrode PB1 is located abovethe contact portion PC, and in contact with the contact portion PCthrough a contact hole which penetrates the third insulating film 13 andthe fourth insulating film 14. The second sub-pixel electrode PB2 islocated above the auxiliary capacitance line C2.

FIG. 4A is a plan view schematically showing a structure of one pixel PXin the counter substrate CT shown in FIG. 1. Here, the plan view in aX-Y plane is shown. In addition, only composition required forexplanation is illustrated, and the dashed line shows a portion of thepixel electrodes PE and the common electrodes CE which are the principalportions of the array substrate.

The counter substrate CT is equipped with a third main-common electrodeCA3 and a second sub-common electrode CB2 which are portions of thecommon electrodes CE. The third main-common electrode CA3 and the secondsub-common electrode CB2 are electrically connected with the electricpower supply portion VS on the outside of the active area in the arraysubstrate AR, or electrically connected with the first main-commonelectrode CA1 formed on the array substrate AR. Thereby, the thirdmain-common electrode CA3 is set to substantially the same commonpotential as the first main-common electrode CA1, etc.

The third main-common electrode CA3 is located on the both sidessandwiching the pixel electrode PE in the X-Y plane, and linearlyextends in the second direction Y. The third main-common electrode CA3is located above the second main-common electrode CA2. The thirdmain-common electrode CA3 is formed in a stripe shape with substantiallythe same width in the first direction X.

In this embodiment, the third main-common electrode CA3 is arranged intwo parallel lines at intervals in the first direction X. The thirdmain-common electrode CA3 includes a third main-common electrode CAL3striding over a boundary between the illustrated pixel PX and a pixeladjoining in the left-hand side end of the illustrated pixel PX, and athird main-common electrode CAR3 striding over a boundary between theillustrated pixel PX and a pixel adjoining in the right-hand side end ofthe illustrated pixel PX. The third main-common electrode CAL3 counterswith the second main-common electrode CAL2. The third main-commonelectrode CAR3 counters with the second main-common electrode CAR2.

The second sub-common electrode CB2 is arranged so as to cross the pixelelectrode PE in the X-Y plane extending in the first direction X. Thesecond sub-common electrode CB2 is connected with third commonelectrodes CAL3 and CAR3 at the both ends thereof. The second sub-commonelectrode CB2 is located above the first sub-common electrode CB1 andthe gate line G1. The second sub-common electrode CB2 is formed in astripe shape along the second direction. The second sub-common electrodeCB2 faces the first sub-common electrode CB1. The second sub-commonelectrode CB2 crosses the third common electrode CA3 above the secondcommon electrode CA3.

In the counter substrate CT, the third main-common electrode CA3 and thesecond sub-common electrode CB2 are covered with a second alignment filmAL2. In the second alignment film AL2, alignment treatment is made alongwith a second alignment treatment direction PD2 to make the liquidcrystal molecule of the liquid crystal layer LQ initial alignment. Here,the alignment treatment is rubbing treatment, optical alignmenttreatment, etc., for example. The second alignment treatment directionPD2 is in parallel to the first alignment treatment direction PD1, andthe same direction as the first alignment treatment direction PD1 inthis embodiment. In addition, the first alignment treatment directionPD1 and the second alignment treatment direction PD2 may be oppositedirections each other, or may be the opposite directions to thedirections shown in the Figure while they are the same directions eachother, i.e., the direction from the first sub-pixel electrode PB1 to thesecond sub-pixel electrode PB2.

FIG. 5 is a cross-sectional view schematically showing the structure ofthe liquid crystal display panel LPN taken along line A-B shown in FIG.2. FIG. 6 is a cross-sectional view schematically showing the structureof the liquid crystal display panel LPN taken along line C-D shown inFIG. 2. FIG. 7 is a cross-sectional view schematically showing thestructure of the liquid crystal display panel LPN taken along line E-Fshown in FIG. 2.

A backlight BL is arranged on the back side of the array substrate AR inthe illustrated example. Various types of backlights BL can be used. Forexample, a light emitting diode (LED) or a cold cathode fluorescent lamp(CCFL), etc., can be applied as a light source of the backlight BL, andthe explanation about its detailed structure is omitted.

The array substrate AR is formed using a first transparent insulatingsubstrate 10. The array substrate AR includes a semiconductor layer SCformed of poly-silicon of the switching element which is not explainedin detail, the gate line G1, the auxiliary capacitance line C1, theauxiliary capacitance line C2, the source line S1, the source line S2,the pixel electrode PE, the first main-common electrode CA1, the secondmain-common electrode CA2, the first insulating film 11, the secondinsulating film 12, the third insulating film 13, the fourth insulatingfilm 14, and the first alignment AL1, etc., in an inside surface of thefirst transparent insulating substrate 10 facing the counter substrateCT.

The semiconductor layer SC is formed between the first insulatingsubstrate 10 and the first insulating film 11. The auxiliary capacitanceline C1, the auxiliary capacitance line C2, and the gate line G1 areformed on the first insulating film 11, and covered with the secondinsulating film 12. The auxiliary capacitance lines C1, the auxiliarycapacitance line C2, and the gate line G1 can be formed simultaneouslyby the same wiring material. The source line S1, the source line S2, andcontact portion PC are formed on the second insulating film 12, andcovered with the third insulating film 13. The source line S1, thesource line S2, and contact portion PC can be formed simultaneously bythe same wiring material. The third insulating film 13 corresponds to afirst interlayer insulating film that covers the source line S1, theswitching element, etc.

The first main-common electrode CA1 and the first sub-common electrodeCB1 are formed on the third insulating film 13, and covered with thefourth insulating film 14. The first main-common electrode CA1 and thefirst sub-common electrode CB1 are formed of transparent electricconductive materials, such as Indium Tin Oxide (ITO) and Indium ZincOxide (IZO), for example.

The fourth insulating film 14 corresponds to a second interlayerinsulating film that covers the first main-common electrode CA1 and thefirst sub-common electrode CB1. The fourth insulating film 14 is formedof a transparent resin material, for example. The fourth insulating film14 eases level difference by the various wirings and electrodes whichare located in the lower layers, and its surface is made approximatelyflat.

The main pixel electrode PA of the pixel electrode PE, the firstsub-pixel electrode PB1, and the second sub-pixel electrode PB2 areformed on the fourth insulating film 14, and covered with the firstalignment film AL1. Moreover, the second main-common electrode CA2 isformed on the fourth insulating film 14 apart from the pixel electrodePE, and covered with the first alignment film AL1. The pixel electrodePE and the second main-common electrode CA2 can be formed simultaneouslyby the same material, and may be formed of transparent electricconductive materials, such as ITO and IZO, or other opaque wiringmaterials, such as aluminum (Al), titanium (Ti), silver (Ag), molybdenum(Mo), tungsten (W), copper (Cu), and chromium (Cr).

The first alignment film AL1 is arranged on the array substrate ARfacing the counter substrate CT, and extends to whole active area ACT.The first alignment film AL1 is arranged also on the fourth insulatingfilm 14. The first alignment film AL1 is formed of the material whichshows a horizontal alignment characteristics.

The counter substrate CT is formed using a second insulating substrate20 which has a transmissive characteristics. The counter substrate CTincludes a black matrix BM, a color filter CF, an overcoat layer OC, thethird main-common electrode CA3, and the second alignment film AL2,etc., in an internal surface of the second insulating substrate 20facing the array substrate AR.

The black matrix BM defines each pixel PX, and forms an aperture APfacing the pixel electrode PE. That is, the black matrix BM is arrangedso that wiring portions, i.e., the source line S, the auxiliarycapacitance line C, and the switching element SW may counter the blackmatrix BM. Herein, the black matrix BM includes a portion located abovethe source lines S1 and S2 extending along the second direction Y, and aportion located above the gate lines G1 and G2 extending along the firstdirection X, and is formed in the shape of a lattice. The black matrixBM is formed in the internal surface 20A of the second insulatingsubstrate 20 facing the array substrate AR.

The color filter CF is arranged corresponding to each pixel PX. That is,while the color filter CF is arranged in the aperture AP defined by theblack matrix in the internal surface 20A of the second insulatingsubstrate 20, a portion thereof extends on the black matrix BM. Thecolors of the color filters CF arranged in adjacent pixels PX in thefirst direction X differ mutually. For example, the color filters CF areformed of resin materials colored by three primary colors of red, blue,and green, respectively. The red color filter formed of resin materialcolored in red is arranged corresponding to the red pixel. The bluecolor filter formed of resin material colored in blue is arrangedcorresponding to the blue pixel. The green color filter formed of resinmaterial colored in green is arranged corresponding to the green pixel.The boundary between the adjacent color filters CF is located in aposition which overlaps with the black matrix BM. Furthermore, the colorfilter CF extends to a plurality of adjacent pixels in the seconddirection Y.

The overcoat layer OC covers the color filter CF. The overcoat layer OCeases influence of concave-convex of the surface of the color filter CF.The overcoat layer OC is formed of a transparent resin material, forexample.

The third main-common electrode CA3 is formed on the overcoat layer OCfacing the array substrate AR, and located under the black matrix BM.The second main-common electrode CAL2 is located under the thirdmain-common electrode CAL3. The second main-common electrode CAR2 islocated under the third main-common electrode CARS. In theabove-mentioned aperture AP, the domain between the pixel electrode PEand the second and third main-common electrodes CA2 and CA3 correspondto a transmissive domain which penetrates the backlight.

The second sub-common electrode CB2 is arranged on the counter substrateCT facing the array substrate AR. The first sub-common electrode CB1 andthe gate line G1 are located under the second sub-common electrode CB2

The second alignment film AL2 is arranged on the counter substrate CTfacing the array substrate AR, and extends to whole active area ACT. Thesecond alignment film AL2 covers the third main-common electrode CA3,the overcoat layer OC, etc. The second alignment film AL2 is formed ofthe materials having horizontal alignment characteristics.

The array substrate AR and the counter substrate CT as mentioned-aboveare arranged so that the first alignment film AL1 and the secondalignment film AL2 face each other. In this case, a pillar-shaped spaceris formed integrally with one of the substrates by resin materialbetween the first alignment film AL1 on the array substrate AR and thesecond alignment film AL2 on the counter substrate CT. Thereby, apredetermined gap, for example, a 2-7 μm cell gap, is formed. The cellgap is smaller than the distance between the main pixel electrode PA andthe first main common electrode CA1. The array substrate AR and thecounter substrate CT are pasted together by seal material arranged in aperipheral of the active area, which is not illustrated, while thepredetermined cell gap is formed, for example.

The liquid crystal layer LQ is held in a cell gap formed between thearray substrate AR and the counter substrate CT, i.e., between the firstalignment film AL1 and the second alignment film AL2. The liquid crystallayer LQ contains the liquid crystal molecules LM. For example, theliquid crystal layer LQ is formed of liquid crystal material whosedielectric anisotropy is positive (posi-type).

A first optical element OD1 is attached on an external surface 10B ofthe array substrate AR, i.e., the external surface of the firstinsulating substrate 10 which forms the array substrate AR by adhesives,etc. The first optical element OD1 is located on a side which counterswith the backlight unit BL of the liquid crystal display panel LPN, andcontrols the polarization state of the incident light which enters intothe liquid crystal display panel LPN from the backlight unit BL. Thefirst optical element OD1 includes a first polarization plate PL1 havinga first polarizing axis AX1. Other optical elements such as retardationfilm may be arranged between the first polarization plate PL1 and thefirst insulating substrate 10.

A second optical element OD2 is attached on an external surface 20B ofthe counter substrate CT, i.e., the external surface of the secondinsulating substrate 20 which forms the counter substrate CT byadhesives, etc. The second optical element OD2 is located on a displaysurface side of the liquid crystal display panel LPN, and controls thepolarization state of emitted light from the liquid crystal displaypanel LPN. The second optical element OD2 includes a second polarizationplate PL2 having a second polarizing axis AX2. Other optical elementssuch as retardation film may be arranged between the second polarizationplate PL2 and the second insulating substrate 20.

The first polarizing axis AX1 of the first polarization plate PL1 andthe second polarizing axis AX2 of the second polarization plate PL2 arearranged in the Crossed Nicole state in which they substantiallyintersects perpendicularly. At this time, one polarization plate isarranged so that its polarizing axis is arranged substantially inparallel with or in orthogonal with the extending direction of themain-pixel electrode PA or the initial alignment direction of the liquidcrystal molecule. In FIG. 4B, the first polarization plate PL1 isarranged so that its first polarizing axis AX1 becomes in parallel tothe first direction X. The second polarization plate PL2 is arranged sothat its second polarizing axis AX2 becomes in parallel to the seconddirection Y. Furthermore, in FIG. 4C, the second polarization plate PL2is arranged so that its second polarizing axis AX2 becomes in parallelto the first direction X. The first polarization plate PL1 is arrangedso that its first polarizing axis AX1 becomes in parallel to the seconddirection Y.

Next, operation of the liquid crystal display panel LPN of theabove-mentioned structure is explained.

At the time of non-electric field state (OFF), i.e., when a potentialdifference (i.e., electric field) is not formed between the pixelelectrode PE and the common electrode CE, the liquid crystal moleculesLM of the liquid crystal layer LQ are aligned so that their long axesare aligned in a parallel direction with the first alignment treatmentdirection PD1 of the first alignment film AL1 and the second alignmenttreatment direction PD2 of the second alignment film AL2 as shown with adashed line in the figure. In this state, the time of OFF corresponds tothe initial alignment state, and the alignment direction of the liquidcrystal molecule LM corresponds to the initial alignment direction.Here, the first alignment treatment direction PD1 and the secondalignment treatment direction PD2 are substantially in parallel with thesecond direction Y and same directions each other. At the time OFF, theliquid crystal molecules LM are initially aligned so that their longaxes are aligned in parallel to the second direction Y in the X-Y planeas shown in the dashed line in the figure. That is, the initialalignment direction of the liquid crystal molecules is in parallel tothe second direction Y.

At the time of OFF, a portion of the backlight from the backlight BLpenetrates the first polarization plate PL1, and enters into the liquidcrystal display panel LPN. The backlight which entered into the liquidcrystal display panel LPN is linearly polarized light which intersectsperpendicularly with the first polarizing axis AX1 of the firstpolarization plate PL1. The polarization state of the linearly polarizedlight does hardly change when the backlight passes the liquid crystallayer LQ at the time OFF. For this reason, the linearly polarized lightwhich penetrates the liquid crystal display panel LPN is absorbed by thesecond polarization plate PL2 which is arranged in the Crossed Nicolspositional relationship with the first polarization plate PL1 (blackdisplay).

On the other hand, in case the potential difference (or electric field)is formed between the pixel electrode PE and the common electrode CE,i.e., at the time of ON, the lateral electric field (or oblique electricfield) is formed in parallel with the substrates between the pixelelectrode PE and the common electrode CE. The liquid crystal molecule LMis affected by the electric field between the pixel electrode PE and thecommon electrode CE, and the alignment state changes. That is, the longaxes of the liquid crystal molecules rotate in the plane substantiallyin parallel to the X-Y plane. Thereby, transmissive regions where thebacklight can penetrate are formed between the pixel electrode PE andthe common electrode CE.

In the embodiment shown in FIG. 4A, in the region between the pixelelectrode PE and the third main-common electrode CAL3 in the upper halfregion of the pixel PX, electric field is formed and interacts betweenthe main-pixel electrode PA and the first sub-pixel electrode PB1 andthe second main-common electrode CAL2, and between the main-pixelelectrode PA and the first sub-pixel electrode PB1 and the thirdmain-common electrode CAL3, respectively. Accordingly, the liquidcrystal molecule LM mainly rotates clockwise to the second direction Y,and turns to the lower left in the figure. Furthermore, in the lowerhalf region of the pixel PX, the electric field is formed and interactsbetween the pixel electrodes of the main-pixel electrode PA and thesecond sub-pixel electrode PB2 and the second main-common electrodeCAL2, between the pixel electrodes of the main-pixel electrode PA andthe second sub-pixel electrode PB2 and the third main-common electrodeCAL3, respectively. Accordingly, the liquid crystal molecule LM mainlyrotates counterclockwise to the second direction Y, and turns to theupper left in the figure. In addition, the electric field between thepixel electrodes of the main pixel electrode PA and the first sub-pixelelectrode PB1 and the first sub-common electrode CB1, and between thepixel electrodes of the main pixel electrode PA and the first sub-pixelelectrode PB1 and the second sub-common electrode CB2 also contributesto the alignment of the liquid crystal molecules LM.

In the region between the pixel electrode PE and the third main-commonelectrode CAR3 in the upper half portion of the pixel PX, electric fieldis formed and interacts between the pixel electrodes of the main-pixelelectrode PA and the first sub-pixel electrode PB1 and the secondmain-common electrode CAR2, and between the pixel electrodes of themain-pixel electrode PA and the first sub-pixel electrode PB1 and thethird main-common electrode CAR3, respectively. Accordingly, the liquidcrystal molecule LM mainly rotates counterclockwise to the seconddirection Y, and turns to the lower light in the figure. Furthermore, inthe lower half portion of the pixel PX, the electric field is formedbetween the pixel electrodes of the main-pixel electrode PA and thesecond sub-pixel electrode PB2 and the second main-common electrodeCAR2, and between the pixel electrodes of the main-pixel electrode PAand the second sub-pixel electrode PB2 and the third main-commonelectrode CAR3, respectively. Accordingly, the liquid crystal moleculeLM mainly rotates clockwise to the second direction Y, and turns to theupper right in the figure. In addition, the electric field between thepixel electrodes of the main pixel electrode PA and the second sub-pixelelectrode PB2 and the first sub-common electrode CB1, and between thepixel electrodes of the main pixel electrode PA and the second sub-pixelelectrode PB2 and the second sub-common electrode CB2 also contributesto the alignment of the liquid crystal molecules LM.

Thus, in each pixel, at the time when the electric field is formedbetween the pixel electrode PE and the common electrode CE, thealignment direction of the liquid crystal molecule LM is divided into aplurality of directions with respect to the region in which the pixelelectrode PE and the first sub-common electrode CB1 (or secondsub-common electrode CB2) overlap each other, and domains are formedcorresponding to each direction. That is, a plurality of domains isformed in each pixel.

At the time of ON, the linearly polarized light which intersectsperpendicularly with the first polarizing axis AX1 of the firstpolarization plate PL1 enters into the liquid crystal display panel LPN,and the polarization state changes when passing the liquid crystal layerLQ in accordance with the alignment state of the liquid crystal moleculeLM. For this reason, at the time of ON, at least a portion of thebacklight which passed the liquid crystal layer LQ penetrates the secondpolarization plate PL2 (white display).

Moreover, according to this embodiment, since the first sub-commonelectrode CB1 is arranged so as to overlap with the gate line G,undesired leaked electric field from the gate line G can be shielded.The first sub-common electrode CB1 functions as a gate shield electrode.Therefore, the influence of undesired electric field in the region closeto the gate line G in the transmissive region is eased, and it becomespossible to control degradation of display grace.

In addition, the second sub-common electrode CB2 is arranged on thefirst sub-common electrode CB1 through the liquid crystal molecule LM.Thereby, since the potentials of the first sub-common electrode CB1 andthe second sub-common electrode CB2 are the same, undesired electricfield is not generated between the first sub-common electrode CB1 andthe second sub-common electrode CB2.

In addition, the electric field between the pixel electrodes of the mainpixel electrode PA and the first sub-pixel electrode PB1 and the firstsub-common electrode CB1, and between the pixel electrodes of the mainpixel electrode PA and the first sub-pixel electrode PB1 and the secondsub-common electrode CB2, the electric field between the pixelelectrodes of the main pixel electrode PA and the second sub-pixelelectrode PB2 and the first sub-common electrode CB1, and between thepixel electrodes of the main pixel electrode PA and the second sub-pixelelectrode PB2 and the second sub-common electrode CB2, also contributesto the alignment of the liquid crystal molecules LM divided into thedomains. Accordingly, when the active area ACT is pressed, even if thealignment state of the liquid crystal molecules LM is temporarilydisturbed, the liquid crystal molecules LM immediately returns to thealignment state in which four domains are formed. That is, it becomespossible to suppress the fall of the display quality by arranging thefirst sub-common electrode CB1 and the second sub-common electrode CB2.

Moreover, according to this embodiment, the array substrate AR includestwo layers of main-common electrodes (the first main-common electrodeCA1 and the second main-common electrode CA2) facing the liquid crystallayer LQ in the circumference of each source line S, to which the samepotential, i.e., the common potential is applied. The first main-commonelectrode CA1 in a lower layer is located adjacent to the source line S.The second main-common electrode CA2 in the upper layer is located rightabove the source line S2. Since the first main-common electrode CA1 andthe second main-common electrode CA2 are set to the same potential, anequipotential surface is formed therebetween. The equipotential surfaceshields undesirable leaked electric field which directs to the liquidcrystal layer LQ from the source line S arranged in the lower layer.That is, the first main-common electrode CA1 and the second main-commonelectrode CA2 can shield undesirable leaked electric field from thesource line S, and can function as a source shield electrode. In thiscase, the first main-common electrode CA1 corresponds to a firstelectric conductive layer of the source shield electrodes, and thesecond main-common electrode CA2 corresponds to a second electricconductive layer of the source shield electrodes. Thus, the influence bythe leaked electric field from the source line S which adjoins the pixelelectrode PE can be eased, and it becomes possible to controldegradation of the display grace by a cross talk.

Moreover, while horizontal electric field (or oblique electric field)required to control the alignment of the liquid crystal molecule betweenthe main pixel electrode PA and the second main-common electrode CA2,and between the main pixel electrode PA and the third main-commonelectrode CA3 is formed at the time of ON according to this embodiment,fringe electric field is formed between the main pixel electrode PA andthe first sub-common electrode CB1 (the second sub-common electrodeCB2). In the X-Y plane, the fringe electric field is substantially inparallel to the above horizontal electric field. For this reason, itbecomes possible to control alignment disorder of the liquid crystalmolecule LM near the gate line G, i.e., in the circumference of thefirst sub-common electrode CB1 and the second sub-common electrode CB2.Thereby, it becomes possible to improve transmissivity near the gateline G, and also to improve the transmissivity in each pixel.

In the example explained her, when the fringe electric field acts on theliquid crystal molecule, the alignment of the liquid crystal molecule isdisordered, and it may become impossible to obtain desiredtransmissivity. However, it becomes possible to reduce the influence bythe fringe electric field to the liquid crystal layer by making thethickness of the fourth insulating film 14 formed of a transparent resinmaterial large. For example, it is preferable to form the film thicknessof the fourth insulating film 14 with approximately 1 μm, when formingthe fourth insulating film 14 with the resin material. Accordingly, itbecomes possible to raise manufacturing yield than the case where thefourth insulating film 14 is formed of the transparent non-organicmaterials.

Moreover, according to this embodiment, although the first main-commonelectrode CA1 is located in the region facing the aperture AP, the firstmain-common electrode CA1 is formed of a transparent electric conductivematerial. At the time of ON, the liquid crystal molecule LM locatedright above the first main-common electrode CA1 is alignment controlledby the electric field formed between the pixel electrode PE and thesecond main-common electrode CA2, and between the pixel electrode PE andthe third main-common electrode CA3. Accordingly, the liquid crystalmolecule LM above the first main-common electrode CA1 also contributesthe display. That is, according to this embodiment, while the firstmain-common electrode CA1 is arranged in the aperture AP, the fall ofthe transmissivity in the aperture AP is not resulted and hightransmissivity is achieved.

Moreover, according to this embodiment, at the time of ON, the liquidcrystal molecule LM in the region which overlaps with the main pixelelectrode PA, the second main-common electrode CA2 and the thirdmain-common electrode CA3 maintains the same initial alignment state asthe time of OFF (or the time of a black display), and does notcontribute to the display. For this reason, in case electrode width ofthe second main-common electrode CA2 and the third main-common electrodeCA3 is formed so as to be larger than the line width of the source lineS, the region which overlaps with an electrode portion which runs offfrom the source line S does not contribute to the display. On the otherhand, according to this embodiment, since the electrode width of thesecond main-common electrode CA2 and the third main-common electrode CA3is smaller than the line width of source line S, it becomes possible toexpand the region in which the alignment of the liquid crystal moleculeLM can be controlled.

Moreover, according to this embodiment, the first main-common electrodeCA1 near the source line S is arranged in the position which is shiftedfrom the region above the source line S. For this reason, it becomespossible to control formation of the undesirable capacitance between thesource line S and the first main-common electrode CA1, and also toreduce the power consumption of the liquid crystal display device.Moreover, the second main-common electrode CA2 facing the source line Sis located more apart from the source line S rather than firstmain-common electrode CA1 and has line width smaller than the sourceline S, it becomes possible to reduce the influence to the display bythe capacitance formed therebetween.

Moreover, according to this embodiment, the liquid crystal molecule LMin the region which overlaps with the second main-common electrode CA2located right above source line S or the region which overlaps with thethird main-common electrode CA3 located under the black matrix BMmaintains the initial alignment state even at the time of ON. For thisreason, even if assembling shift between the array substrate AR and thecounter substrate CT arises, the leak of undesirable electric field tothe adjoining pixel can be controlled. Therefore, even if it is a casewhere the colors of color filter CF differ between the adjoining pixels,it becomes possible to control generating of mixed colors. Moreover,even if it is a case where the liquid crystal display panel is observedfrom an oblique direction, since the backlight does not penetrate theregion which overlaps with the second main-common electrode CA2 or thethird main-common electrode CA3, it becomes possible to controlgenerating of mixed colors.

Moreover, according to this embodiment, it becomes possible to form aplurality of domains in one pixel. For this reason, a viewing angle canbe optically compensated in the plurality of directions, and wideviewing angle can be attained.

According to this embodiment, in the common electrode CE, the firstmain-common electrode CA1 and the first sub-common electrode CB1 areelectrically connected mutually, the second main-common electrode CA2 iselectrically connected with the first main-common electrode CA1, and thethird main common electrode CA3 is electrically connected with the firstmain common electrode CA1, etc. Furthermore, the third main commonelectrode CA3 is electrically connected with the second sub-commonelectrode CB2. For this reason, even if disconnection occurs in thecommon electrodes CE, it becomes possible to supply common potentialstably, and to control the generation of a poor display.

In addition, although the above-mentioned embodiment explains the casewhere the initial alignment direction of the liquid crystal molecule LMis in parallel to the second direction Y, the initial alignmentdirection of the liquid crystal molecule LM may be the oblique directionwhich obliquely crosses the second direction Y.

Moreover, in this embodiment, although the case where the liquid crystallayer LQ is formed of the liquid crystal material which has positive(positive type) dielectric constant anisotropy, the liquid crystal layerLQ may be formed of the liquid crystal material which has negative(negative type) dielectric constant anisotropy.

As explained above, according to the embodiments, it becomes possible tosupply the liquid crystal display device which can control degradationof display grace.

While certain embodiments have been described, these embodiments havebeen presented by way of embodiment only, and are not intended to limitthe scope of the inventions. In practice, the structural elements can bemodified without departing from the spirit of the invention. Variousembodiments can be made by properly combining the structural elementsdisclosed in the embodiments. For embodiment, some structural elementsmay be omitted from all the structural elements disclosed in theembodiments. Furthermore, the structural elements in differentembodiments may properly be combined. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the inventions.

What is claimed is:
 1. A liquid crystal display device, comprising: afirst substrate including; a gate line extending in a first direction, asource line extending in a second direction orthogonally crossing thefirst direction, a switching element electrically connected with thegate line and the source line, a first interlayer insulating filmcovering the switching element, a first sub-common electrode formed onthe first interlayer insulating film and extending in the firstdirection, the first sub-common electrode facing the gate line, a firstmain-common electrode formed on the first interlayer insulating film andconnected with the first sub-common electrode, the first main-commonelectrode extending along the source line in the second direction, asecond interlayer insulating film covering the first sub-commonelectrode and the first main-common electrode, a second main-commonelectrode formed on the second inter insulating film and extending inthe second direction so as to face the source line, the secondmain-common electrode set to the same potential as the first main-commonelectrode, a main-pixel electrode formed on the second interlayerinsulating film and extending in the second direction so as to cross thefirst sub-common electrode, the main-pixel electrode electricallyconnected with the switching element, and a first alignment filmcovering the second main-common electrode and the main-pixel electrode;a second substrate including; a third main-common electrode extending inthe second direction so as to face the second main-common electrode, thethird main-common electrode set to the same potential as the secondmain-common electrode, a second sub-common electrode connected with thethird main common electrode, the second sub-common electrode extendingin the first direction so as to face the first sub-common electrode, anda second alignment film covering the third main-common electrode and thesecond sub-common electrode, a liquid crystal layer held between thefirst substrate and the second substrate.
 2. The liquid crystal displaydevice according to claim 1, wherein the first substrate furtherincludes a first auxiliary capacitance line and a second auxiliarycapacitance line extending in the first direction, respectively, and thegate line is arranged in a central portion between the first auxiliarycapacitance line and the second auxiliary capacitance line.
 3. Theliquid crystal display device according to claim 2, wherein the firstsubstrate further includes a first sub-pixel electrode connected withone end of the main-pixel electrode so as to locate on the firstauxiliary capacitance line and extending in the first direction, and asecond sub-pixel electrode connected with the other end of themain-pixel electrode so as to locate on the second auxiliary capacitanceline and extending in the first direction.
 4. The liquid crystal displaydevice according to claim 3, wherein the first substrate furtherincludes a contact portion located on the first auxiliary capacitanceline and electrically connected with the switching element, and thefirst sub-pixel electrode contacts with the contact portion.
 5. Theliquid crystal display device according to claim 3, wherein the width ofthe first sub-pixel electrode is larger than the width of the secondsub-pixel electrode.
 6. The liquid crystal display device according toclaim 1, wherein the first main-common electrode is formed of atransparent conductive material, and arranged on the main-pixelelectrode side rather than a region overlapping with the source line,and the width of the second main-common common electrode is smaller thanthe width of the source line, and arranged in a region overlapping withthe source line.
 7. The liquid crystal display device according to claim1, wherein the first main-common electrode and the sub-common electrodeare formed of transparent conductive materials, such as Indium Tin Oxide(ITO) and Indium Zinc Oxide (IZO).
 8. The liquid crystal display deviceaccording to claim 1, wherein a first optical element including a firstpolarization plate having a first polarizing axis is attached on anexternal surface of the first substrate, and a second optical elementincluding a second polarization plate having a second polarizing axis isattached on an external surface of the second substrate.
 9. The liquidcrystal display device according to claim 8, wherein the firstpolarizing axis and the second polarizing axis are arranged in theCrossed Nicols state in which they substantially intersectsorthogonally, and one of the first and second polarization axes isarranged substantially in parallel with or in orthogonal with anextending direction of the main-pixel electrode.
 10. A liquid crystaldisplay device, comprising: a first substrate including; a gate lineextending in a first direction, a source line extending in a seconddirection orthogonally crossing the first direction, a switching elementelectrically connected with the gate line and the source line, a gateshield electrode extending in the first direction and facing the gateline, a source shield electrode extending in the second direction so asto face the source line, the source shield electrode set to the samepotential as the gate shield electrode, and a main pixel electrodeextending in the second direction so as to cross the gate shieldelectrode, the main pixel electrode being apart from the source shieldelectrode and electrically connected with the switching element, asecond substrate including; a main-common electrode facing the sourceshield electrode and extending in the second direction, the main-commonelectrode set to the same potential as the source shield electrode; anda sub-common electrode connected with the main common electrode andextending in the first direction so as to face the gate shieldelectrode, a liquid crystal layer held between the first substrate andthe second substrate.
 11. The liquid crystal display device according toclaim 10, wherein the source shield electrode is formed of a firstconductive layer extending along the source line and a second conductivelayer arranged on the source line.
 12. The liquid crystal display deviceaccording to claim 10, wherein the first substrate further includes afirst auxiliary capacitance line and a second auxiliary capacitance lineextending in the first direction, respectively, and the gate line isarranged in a central portion between the first auxiliary capacitanceline and the second auxiliary capacitance line.
 13. The liquid crystaldisplay device according to claim 12, wherein the first substratefurther includes, a first sub-pixel electrode connected with one end ofthe main-pixel electrode so as to locate on the first auxiliarycapacitance line and extending in the first direction, and a secondsub-pixel electrode connected with the other end of the main-pixelelectrode so as to locate on the second auxiliary capacitance line andextending in the first direction.
 14. The liquid crystal display deviceaccording to claim 13, wherein the first substrate further includes, acontact portion located on the first auxiliary capacitance line andelectrically connected with the switching element, and the firstsub-pixel electrode contacts with the contact portion.
 15. The liquidcrystal display device according to claim 13, wherein the width of thefirst sub-pixel electrode is larger than the width of the secondsub-pixel electrode.
 16. The liquid crystal display device according toclaim 11, wherein the first conductive layer is formed of a transparentconductive material, and arranged on the main-pixel electrode siderather than a region overlapping with the source line, and the width ofthe second conductive layer is smaller than the width of the sourceline, and arranged in a region overlapping with the source line.